Mortality in Cushing's syndrome: systematic analysis of a large series with prolonged follow-up

In this study, we aim to assess the long-term survival and causes of death in a retrospective cohort study on patients with all aetiologies of endogenous Cushing's syndrome (CS) (except adrenal cancer), presenting to two large tertiary endocrine referral centres, and to identify variables predicting mortality.

The records of all patients presenting with endogenous CS in the Department of Endocrinology, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK and the Department of Endocrinology, 'Evangelismos' General Hospital, Athens, Greece between 1967-2009 (Oxford series) and 1962-2009 (Athens series) were reviewed. The standardised mortality ratio (SMR) was calculated for the Oxford series.

In total, 418 subjects were identified (311 with Cushing's disease (CD), 74 with adrenal Cushing's (AC) and 33 with ectopic Cushing's (EC)). In CD, the probability of 10-year survival was 95.3% with 71.4% of the deaths attributed to cardiovascular causes or infection/sepsis. SMRs were significantly high overall (SMR 9.3; 95% CI, 6.2-13.4, P<0.001), as well as in all subgroups of patients irrespective of their remission status. In AC, the probability of 10-year survival was 95.5% and the SMR was 5.3 (95% CI, 0.3-26.0) with P=0.2. Patients with EC had the worst outcome with 77.6% probability of 5-year survival.

In this large series of patients with CS and long-term follow-up, we report that in CD the mortality is significantly affected, even after apparently successful treatment. The SMR of patients with AC was high, but this was not statistically significant. The implicated pathophysiological mechanisms for these findings need to be further elucidated aiming to improve the long-term outcome.